The present invention relates to sound quality adjustment devices for various audio apparatus and television receivers.
Among examples of the sound quality adjustment devices for various audio apparatus are those disclosed in Japanese Patent Publication Nos. 3206271 and 3329050. FIG. 13 is a block diagram showing a general construction of the sound quality adjustment devices disclosed in the above-identified Nos. 3206271 and 3329050 publications. In the sound quality adjustment device of FIG. 13, input audio or sound signals of two channels, i.e. left (L) and right (R) channels, are attenuated by attenuators 100a and 100b, respectively, and then levels of particular frequency bands of these two-channel input sound signals are enhanced or boosted by tone filters 101a and 101bThen, the thus-boosted sound signals are determined by a level determination section 102, and filter coefficients of the tone filters 101a and 101b are varied by a boost amount calculation section 103, on the basis of the results of the level determination, so as to achieve desired sound quality adjustment.
However, with the conventional sound quality adjustment device of FIG. 13, where the level boost amounts of the tone filters 101a and 101b are adjusted by feedback control based on detection of the levels of the sound signals processed by the tone filters 101a and 101b, there would arise the problem that the level boost amount adjustment is delayed relative to a rapid level variation of any of the input sound signals. Thus, when any of the input sound signals has rapidly increased in level, for example, a considerable time is required before the level boost amount is appropriately restrained through the feedback control, so that “clipping” may result due to, for example, an overflow of digital signal processing and an undesired clipping sound may be produced at connection points of the boost amount adjustment.